This project was terminated during this year with the P.I.'s departure from NINDS. The project was originally undertaken primarily to investigate biochemical abnormalities of CNS white matter in neuro-AIDS indicated by the wide spread myelin pallor (decreased staining with luxol fast blue) observed histologically. the principal findings were: 1) Although the myelin pallor suggested substantial myelin loss, both the quantitative biochemical analyses of myelin proteins in postmortem subcortical white matter samples from AIDS patients and immunohistochemical observations showed that there was actually very little demyelination. 2) There was significant accumulation of serum proteins in the white matter indicating a breakdown of the blood brain barrier that may contribute to CNS pathology in neuro-AIDS. The myelin pallor observed histologically was probably related to the accumulation of fluid in the white matter. Also of interest was the substantial conversion of MAG to a proteolytic cleavage product (dMAG) in some of the AIDS samples as is observed multiple sclerosis lesions, which are also associated with breakdown of the blood brain barrier. This proteolytic conversion of MAG to dMAG, which may be related to perturbation of the blood brain barrier, and its relationship to white matter pathology is continuing to be studied as part of the project entitled "Disorders of CNS Myelin" (Z01 HNQ 02848 LMCN). Any future research on myelin abnormalities in neuroAIDS will also be incorporated into that continuing project.